Statistics Question: Years to Earn Bachelor's Degree

Years to Earn Bachelor's Degree: Listed below are the lengths of time (in years) it took for a random sample of college students to earn bachelor's degrees (based on data from the National Center for Education Statistics). Based on these results, does it appear that it is common to earn a bachelor's degree in 4 years?

Years to Earn Bachelor's Degree 4 4 4 4 4 4 5 5 5 5 5 5 6 6 8 9 9 13 13 15

2 answers

Define "common."
As indicated previously, if something happened 6 out of 20 times would you call that common?